Information about the external world arrives at our brain via sensory system. Sensory stimuli interact with receptor neurons in the periphery to generate sensation. Interpretation of the peripheral neural activity by the central circuitry leads to perception of the external world. What features of an animal's sensory world are relevant to behavior? How are the important sensory cues processed in the central brain to generate appropriate behavioral output? This proposal focuses on studying the neural representation of innately attractive and aversive odorants at the level of both primary and secondary sensory processing centers in an effort to uncover hard wired neural circuits that encode negative or positive valence in a simple model organism. The proposed experiments will be carried out in Drosophila, an organism with an anatomically simple olfactory system that is amenable to molecular and genetic manipulations, optical imaging technologies, and behavioral analysis. The experiments outlined here investigate the hypothesis that innately attractive and aversive odorants are encoded by separate labeled-line circuits. The goals of these experiments are: 1) to define key circuit elements at the level of the antennal lobe, a primary sensory processing center for olfaction, that mediate attraction or aversion to olfactory stimuli;2) to examine the representation of attractive and aversive odorants at higher brain center such as the mushroom body. These findings would then serve as a platform for launching a longer-term project directed at olfactory perception and decision- making at higher brain centers, where valence is assigned to stimuli encountered in the environment for appropriate motivated behaviors. PUBLIC HEALTH RELEVANCE: Drug addiction through neural circuit of reward signal has a profound impact on sensory perception. The work of this proposal is basic science that seeks to reveal the neural circuit underlying olfactory perception, creating a knowledge base from which potential neuron population can be evaluated for future therapeutic interventions of drug addiction.